You Can Treat Depression With Magnets — But Scientists Have No Idea How It Works

A schematic showing how
TMS stimulates the left prefrontal cortex, activating areas
deeper in the brain.Neurostar

Drugs are the most common psychiatric treatment for depression.
But about 40 percent of people fail to respond to this
first-line of antidepressants. What to do? The answer to date has
often been more and different drugs.

But transcranial magnetic stimulation (TMS), a technique that can
revive activity in neurons in the brain's prefrontal cortex using
an electromagnet, has been receiving more attention as a possible
treatment for these stubborn cases of depression. In 2008, the
FDA approved TMS for this purpose. Data since that point has been
promising, but questions remain: How does it compare to
antidepressant drugs? Is it cost-effective?

Research presented today (May 6) at the American Psychiatric
Association's annual meeting in New York suggests that the
technique is perhaps better than previously thought. In the
study, the researchers compared two groups: those who had
received TMS after failing to respond to drugs, and those who
were given new antidepressants after not getting better on prior
meds. The finding: 53 percent of those receiving TMS had no or
mild depression after six weeks of treatment, compared with 38
percent taking a new or augmented type of antidepressant.

The study also looked at the economics. It found that TMS therapy
would cost about $1,000 per patient per year, which is considered
quite affordable, according to study co-author Kit Simpson, an
economist at the Medical University of South Carolina. Over the
course of two years, TMS would actually become more affordable
than the current default of additional rounds of drug therapy,
said Dr. Mark Demitrack, a study co-author and chief medical
officer of Neuronetics, which makes a widely-used type of TMS
called the NeuroStar TMS Therapy System.

The data seems to suggest that TMS 'might be more effective than
drugs.'

The results show the technique is better than drugs for this type
of depression, Dr. Demitrack told Popular Science.

"Until now there has been a lot of research showing its efficacy
but mostly compared to placebo, not other treatments," said Paul
Fitzgerald, a researcher at Monash University in Melbourne,
Australia, who wasn't involved in the study. "It is clearly very
safe, better tolerated than medication and now the data seems to
suggest that it might be more effective."

But there are some caveats. It should first be noted that this
was not was not a randomly-assigned, placebo-blind study, the
gold standard in gauging how effective treatments are, said Dr.
Philip Janicak, at Rush University, who wasn't involved in the
research. Rather, it compared two different groups of patients.
The first group consisted of 307 patients who were treated with
TMS at 42 clinics throughout the U.S., after failing to respond
to drugs. The second group, or rather second pool of data, was
taken from a previous nationwide study, completed in 2006, of
patients who were given new antidepressant medications after
failing to respond to previous drug therapy. The patients in the
latter group were chosen to match the former group as closely as
possible, on measures such as sex, age, severity of illness, etc.

Another factor to consider is that most (about 90 percent) of the
patients receiving TMS were still taking their old
antidepressants, Dr. Janicak added.

That said, Dr. Janicak has been treating patients with TMS for 15
years, and has seen the technique turn around people's lives. "I
have to say I am amazed... we are seeing very significant
improvements in these patients," he told Popular
Science. Dr. Janicak's work has shown that about 55 to 60
percent of patients who have failed to respond to antidepressants
respond to this technique, and see at least a 50 percent
improvement in measures of their depression. About 35 percent of
those patients have "remitted," with enormous reductions in
measures of depression, and some are no longer clinically
depressed.

In TCM therapy, an electromagnet is applied to the left side of
the forehead. This induces currents in neurons in the left
prefrontal cortex--where brain imaging studies have shown a
deficit in activity in depressed patients. It is thought that
this can induce activity and blood flow to this area, but also
causes changes in areas deeper in the brain (responsible for mood
regulation) to which neurons in the cortex connect. Side effects
of TCM tend to be mild, especially compared to antidepressants,
and the most common complaint is a mild headache, Simpson said.

Exactly how TCM works is a mystery, Dr. Janicak said. But the
same can be said of antidepressants, he added.